Ok so depending on floor colours and overall look that she is going for I think (if she is really adamant) that the blue could work if you change the Amaro cabinets to a whiter shade - this will give it an overall crisp, oceanside feel with the warmth of the soft walnut. Otherwise I would contrast it more with a mid-tone colour splashback in grey/brown tones. Again this totally depends of her tastes... Here's a photo that you could show her with the blue splashback - granted it is a little deeper than her selection but at least she can see it on a realistic scale and of course the timber/white cabinets are flipped in this one. Hope some of that helps!

Have you already sourced your tiles? I would expect most tile stores could help you find the edging tiles which I think are typically termed 'pencil' tiles for the style you have shown. We used bevelled subway tiles in our DIY ensuite. In hindsight we would have aimed to finish the brick pattern with 1/3 and 2/3 sized tiles (like in your pic 1) rather than full and 1/2 (pic2 and 3) to give a more even edge thickness/profile... Might not suit and we didn't use capping tile (I lost that arguement!) so it is probably more obvious in our bathroom, but just something you might like to consider.

We have tiles that do not have a gloss finish. They are Encaustic, or at least I think that is what the style is called.

Edwards tiles are well-known as the leading Bluestone pavers Melbourne company that offers the services at affordable rates. Our customers can confidently rely on us for quality services. We make use of the quality products to make sure that our services remain till last. If you’re looking for stone tiles to complement the garden or pool pavers then our experts can guide you in finding the best service that fits your home. To learn more about us and our services you can call us at 03 9544 9544